Prostate-specific antigen (PSA) and PSA density: racial differences in men without prostate cancer.
BACKGROUND: Many physicians now use serum prostate-specific antigen (PSA) to screen for prostate cancer in asymptomatic men. Whether or not a prostate biopsy should also be performed depends on an accurate definition of what constitutes a normal PSA value. Until recently, studies conducted to establish normal serum PSA values have involved study populations that have included few African-American men. PURPOSE: We sought to compare serum PSA levels and PSA density (i.e., serum PSA level/prostate volume ratio) in African-American and white men without histologic evidence of prostate cancer. METHODS: We reviewed the medical records of 826 consecutive men who underwent one or more prostate biopsies at the Veterans Affairs Medical Center in Shreveport, LA, from January 1993 through December 1995. In this retrospective review, we recorded patient's age, race, serum PSA level, digital rectal examination result, ultrasound-determined prostate volume, indications for biopsy, and biopsy results. Data from a total of 752 consecutive men who were either white or African-American and whose indication for biopsy included a serum PSA of greater than 4.0 ng/mL and/or an abnormal digital rectal examination were analyzed. To examine possible differences in serum PSA level, PSA density, prostate volume, and patient age, the two-sided Student's t test was employed. Multivariate linear regression analysis was used to determine if serum PSA levels were associated with the patient's age, race, or prostate volume in men without prostate cancer. RESULTS: Of the 752 men included in this analysis, 254 had histologic evidence of prostate cancer and 498 did not. Of the 498 men without prostate cancer, 367 (74%) men were white and 131 (26%) were black. There were no racial differences in age or calculated prostate volume. Serum PSA levels and calculated PSA density, however, were significantly (both P < .0001) higher in African-American men that in white men. A multivariate linear regression analysis indicated that race and prostate volume were independent variables associated with serum PSA level. For African-American and white men, serum PSA values of greater than 4 ng/mL were associated with prostate cancer with sensitivities of 89.5% and 81.9%, respectively, and specificities of 38.2% and 52.3%, respectively. CONCLUSION: Among biopsied men without histologic evidence of prostate cancer, African-Americans have a significantly higher PSA level and PSA density than similarly aged white men. IMPLICATIONS: Published criteria for normal PSA level and density have been derived primarily from white men and may not be directly applicable to other populations. Race-specific data are needed to fully optimize PSA as a tumor marker in racial populations that are at high risk for prostate cancer death.